The overall goal of this proposal is to understand better how to reduce asthma morbidity and health care utilization among low-income, ethnically diverse children age 3-13. In particular, evidence about the effectiveness of in-home interventions, emphasizing control of environmental triggers relative to clinic-based interventions, is needed. One-half of the participants will receive clinic-based asthma education, self-management support (an asthma action plan and self-monitoring), resources for asthma control (allergy control bedding covers, a peak flow meter, and a medication spacer) and care coordination for one year from an asthma nurse (level 1 intervention). The other half will receive these services plus in-home environmental assessment, an individualized home action plan based on assessment data, education, and social support, encouragement of behavior changes, materials to reduce exposures (bedding covers, vacuums, door mats, cleaning kits, and a HEPA filter), and asthma self-management support for one year from a community health worker (level 2 intervention). A second goal is to learn how to adapt these interventions so they are culturally appropriate for ethnically diverse populations. A third goal is to reduce exposures to other household health risks such as lead, dust, asbestos, pesticides, other toxic household chemicals, and risks for injuries. A fourth goal is to develop better tools for assessing the indoor environment in community-based settings. A final goal is to integrate these activities into the work of the local asthma coalition. The investigators will conduct a randomized controlled trial with 360 subjects using parallel intervention groups and a wait-list control group to compare the effectiveness of the level 1 and 2 interventions with each other and the control group. Primary outcome measures will include asthma-related health status and quality of life, medical care utilization, and exposure to indoor asthma triggers (mites, roaches, mold, tobacco smoke, and pets). Secondary measures include knowledge of asthma, control of environmental triggers, and medical management; self-efficacy; and behaviors related to asthma control. They will assess the costs of the two levels of intervention from the perspective of a health services payer. The investigators hope this research will result in a replicable and sustainable model which can be adopted by health insurers and health care delivery organizations and integrated into a comprehensive, coordinated local asthma control system. The project's organization is based upon partnerships between parents of children with asthma, community-based organizations, public health agencies, and academia, and will follow principles of community-based collaborative research. It is sponsored by the King County Asthma Forum, a local asthma coalition with broad community participation from people with asthma, their families, and 34 agencies, including Public Health - Seattle & King County, the American Lung Association of Washington, the Asthma and Allergy Foundation of American, school districts, community health centers, hospitals, Seattle University, and the University of Washington.